SSW7000 | 3-3
3.1.6. Bypass Contactor
The SSW7000 with frames A, B and C have a vacuum contactor with utilization category AC-3, which makes it
possible to bypass the power arms after starting the motor. This function allows energy saving by eliminating
losses on the SCRs during the motor full operating duty and it also eliminates the necessity of using fans for the
operation of the SSW7000 in its rated start operation duty, which is specified in the section 9.1 – Power Data.
This contactor is sized to withstand direct on line starting and the SSW7000 rated current at full load. It also allows
the implementation of a direct on line starting logic.
The bypass contactor is driven by the SSW7000 control electronics.
3.1.7. Bypass Circuit Breaker
The SSW7000 with frame D has a vacuum circuit breaker which makes it possible to bypass the power arms after
starting the motor. This function allows energy saving by eliminating losses on the SCRs during the motor full
operating duty and it also eliminates the necessity of using fans for the operation of the SSW7000 in its rated start
operation duty, which is specified in the section 9.1 – Power Data.
This circuit breaker is sized to withstand direct on line starting and the SSW7000 rated current at full load. It also
allows the implementation of a direct on line starting logic.
The bypass circuit breaker is driven by the SSW7000 control electronics.
3.1.8. Power Arms
The SSW7000 power arms are assembled as modules with wheels that facilitate their installation and replacement
during maintenance. For the SSW7000C version, the power arms don’t have wheels and are attached to the back
of the panel.
(a) SSW7000A (b) SSW7000C
Figure 3.3: Power Arms
Each arm is comprises the SCRs, heatsinks, snubbers, supply transformers and firing boards. The firing
commands and the temperature readings are performed through fiber optic cables.
If it is necessary to increase the start duty of the SSW7000, increasing the number of starts per hour, for instance,
it is possible to install fans on the power arms. In such case, refer to the manufacturer.
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